Method for Scouring Wool

ABSTRACT

The present invention provides for a method for scouring wool by contacting the wool with an aqueous composition comprising an alcohol alkoxylate, water, and optional additives such as hydrotropes serving as stabilizer and/or dispersant. The compositions were found to exhibit both high detergency in wool scouring, and high stability when stored at room temperature or a lower temperature, while still remain lanolin recovery rate at a high level.

TECHNICAL FIELD

This invention relates to a method for scouring wool, specificallyrelates to a method for scouring wool with a composition comprising analcohol alkoxylate.

BACKGROUND

Wool straight off a sheep, known as “greasy wool” or “wool in thegrease”, contains a high level of lanolin, as well as dirt, dead skin,sweat residue, pesticide, and vegetable matter. Before the wool can beused for commercial purposes, it must be scoured via a process ofcleaning the greasy wool. Scouring may be as simple as a bath in warmwater, or as complicated as an industrial process using detergent andalkali, and specialized equipment.

Lanolin removed from wool is valuable, for example, it is widely used incosmetic products such as hand creams. Typically, lanolin is extractedby washing the wool in hot water with a special wool scouring detergentto remove dirt, wool grease (crude lanolin), suint (sweat salts), andanything else stuck to the wool. The wool grease is continuously removedduring this washing process by centrifugal separators, which concentrateit into a wax-like substance melting at approximately 36˜42° C. (96˜108°F.).

Like many natural products, lanolin is complex and variable incomposition. For example, a typical high purity grade of lanolin iscomposed predominantly of long chain waxy esters (about 97% by weight)with the remainder being lanolin alcohols, lanolin acids and lanolinhydrocarbons. An estimated 8,000 to 20,000 different types of lanolinesters are present in lanolin, resulting from combinations between the200 or so different lanolin acids and the 100 or so different lanolinalcohols identified so far. Due to lanolin's complex composition of longchain esters, hydroxy esters, diesters, lanolin alcohols, and lanolinacids, it has been always required to develop a detergent that iscapable of removing lanolin and impurities from wool efficiently andquickly.

Generally, there are two key criteria in evaluating a detergent used forwool scouring: 1) degreasing efficiency which is usually characterizedby whiteness of the cleaned wool and the residual grease on the wool;and 2) lanolin recovery efficiency from the waste water. For a newdeveloped detergent, both the criteria need to be comparable or betterto conventional detergents used in the wool scouring industry, wherebyit is preferred that both quantity and quality, i.e. the absence ofcontaminants, of the lanolin is optimized to maximize the economicbenefits. Moreover, environmental aspects of the proposed detergent willalso need to be taken into consideration. Therefore it is preferred tohave a highly efficient detergent, so that small quantities of detergentcan be used, which is further preferred to be easily biodegraded.

WO 94/00508 disclosed that compounds derived from alkenyl succinicanhydrides having particularly C₁₄ to C₂₂ alk(en)yl groups and/orsubstituents of functional groups elsewhere around the molecule givematerials which have significantly and surprisingly differentproperties. In particular they perform well as nonionic surfactants,particularly in aqueous systems, having unexpected cloud pointproperties indicating good performance at elevated temperatures and havegood behavior in alkaline conditions. Also the surfactants have goodbiodegradation properties. End uses for the surfactant were alsodisclosed, which include wool scouring. It was mentioned that thesurfactants are very effective wool scouring surfactants, in particularretaining their activity well after multiple scouring cycles, even whenused in scouring wool with very fine fibers. The reference disclosed theparticular surfactants with good performances in wool scouring, yet didnot focus on a composition which includes the surfactants and using suchspecific combinations as detergent for wool scouring process.

WO 99/16942 disclosed a method of scouring and chemically processingwool or other like fiber in a modified scour in order to produce scouredfibers greatly improved in respect of a number of important qualityparameters. Generally, the method involved a series of processes to havefibers such as wool subjected to acid extraction, bleaching, chemicalreduction, and treatments with detergents and dispersant step by step,wherein a nonionic detergent was used for scouring the fibers, a lowfoaming nonionic detergent together with a dispersing agent and anoptional reducing agent was used for extra scouring the fibers, and EDTAtogether with sulphuric acid and optional reducing agent was used foriron extraction from the fibers. The method is a complex process whichis a combination of different treatment steps, wherein differentchemicals are used for the different treatment steps, respectively.

DESCRIPTION OF THE INVENTION

The present invention provides for a method for scouring wool with acomposition comprising an alcohol alkoxylate. The composition is capableof degreasing wool at a relatively lower dosage, and of removing lanolinor grease from the wool more quickly. Moreover, the composition hasexcellent storage stability, which overcomes some of the storageproblems observed with conventional detergents.

The present invention developed a series of wool scouring detergentsbased on an aqueous composition comprising an alcohol alkoxylate, waterand optional additives including, but not limited to, quaternaryammonium compounds serving as hydrotrope, polymeric dispersants forsuspending dirt particles and for preventing stain re-deposition,chelate agents for chelating metal ions such as Ca²⁺, Mg²⁺, and fillersfor improving antifreeze stability of the formulation and for modifyingthe rheology of the product. The compositions according to the presentinvention were found to exhibit both high detergency in wool scouring,and high stability over wide temperature range, along with an increasein the lanoline recovery efficiency and purity.

According to the present invention, the alcohol alkoxylate used as thesurfactant is in the form of an alcohol alkoxylate mixture with thefollowing general formula (I):

RO(AO)_(n)—H   (I)

Wherein R represents linear or branched hydrocarbyl group having 4 to 22carbon atoms; preferably having 6 to 13 carbon atoms; more preferablyhaving 9 to 11 carbon atoms.

AO represents a C₂-C₆ alkyleneoxy unit, n is from 1 to 20, preferablyfrom 2 to 9, more preferably from 4 to 7. “n” means the moles ofalkyleneoxy unit addition per mole of the surfactant of formula (I),which is an average value.

The solubility of the detergent and its ability to emulsify lanolin arerelated to the HLB value of the alcohol alkoxylates used in thecomposition. Unless otherwise indicated in the present invention, theHLB value is calculated according to Davies scale (0-40), for bothcationic and nonionic surfactants mentioned in the present invention.Generally, the length of both the hydrophobic alkyl chain and thehydrophilic alkyloxy chain of alcohol alkoxylates determines theresulting HLB value of alcohol alkoxylates. Preferably the alcoholalkoxylates used in the present invention have an HLB of from 10.0 to15.0. In addition, by including alcohol alkoxylates with alkyloxy chainas defined above, the cloud point of the resulting wool scouringcomposition is kept within a range such that the alcohol alkoxylatesremain stable during the wool scouring process, while become cloudy orphase separated when the temperature is raised to or above thetemperature for lanolin recovery. This is because the alcoholalkoxylates do not behave as an effective emulsifier at a temperaturehigher than the cloud point. As a result, easier demulsification oflanolin was found to be achieved in lanolin recovery process. Moreover,the alcohol alkoxylates with relatively short hydrophilic alkyloxy chainaccording to the present invention were found to have improvedbiodegradation properties in comparison with those having longerhydrophilic alkyloxy chain, and they are therefore more environmentalfriendly.

Surprisingly, it has also been found that the alkyleneoxy unitsdistribution in the alcohol alkoxylate showed great influence on lanolindetergency and recovery. Specifically, when alcohol alkoxylates ofnarrow range alkyleneoxy units distribution were used as surfactant inthe detergent composition of the present invention, they were observedto result in more effective detergency, and more complete separation oflanolin than those observed with broad range distribution of alkyleneoxyunits.

The alcohol alkoxylate used according to the present invention is amixture which inherently include residue of unreacted alcohol, alcoholalkoxylates with low addition of alkyleneoxy unit, as well as alcoholalkoxylates with excessively high addition of alkyleneoxy unit. Withoutwishing to be bound by existing theory, it was seen that the residue ofunreacted alcohol and alcohol alkoxylates with low addition ofalkyleneoxy unit may result in unwanted odor of the degreased wool, andthat the alcohol alkoxylates with excessively high addition ofalkyleneoxy unit may adversely increase cloud point of the mixturealcohol alkoxylates, for example, to a temperature above the lanolinrecovery temperature, which decreases lanolin recovery efficiency.

When used herein, the term “narrow range” means the alcohol alkoxylatefor use in the composition has a narrower distribution of the moles ofalkyleneoxy addition than a normal alcohol alkoxylate, i.e., “broadrange” alcohol alkoxylate. Specifically, the narrow range alcoholalkoxylate used in the present invention has a distribution of the molesof alkyleneoxy units addition not greater than 20, preferably notgreater than 9, and more preferably not greater than 7, meanwhile themoles of alkyleneoxy units is preferably not less than 2, and morepreferably not less than 4. One of ordinary skill in the art wouldunderstand that, due to the preparation process of alcohol alkoxylates,the final product is actually in the form of a mixture of alcoholalkoxylates having different moles of alkyleneoxy units addition, aswell as low content of raw material such as unreacted alcohols. Fornormal processes using KOH, NaOH or the likes as the alkoxylationcatalyst to produce alcohol alkoxylates, the distribution of the molesof alkyleneoxy units addition is broad; and for specific processes suchas, for example, the process according to EP 0845449 B1 filed by AKZONOBEL N.V. on Nov. 24, 1997, narrower distribution of the moles ofalkyleneoxy units addition was achieved than those obtained with normalprocesses.

According to the present invention, the narrow range mixture of alcoholalkoxylates is such that, not less than 40 wt %, preferably not lessthan 60 wt %, more preferably not less than 70 wt %, of the alcoholalkoxylates has a distribution of the moles of alkyleneoxy unitsaddition not greater than 20, preferably not greater than 9, and morepreferably not greater than 7, meanwhile the moles of alkyleneoxy unitsaddition is preferably not less than 2, and more preferably not lessthan 4.

The alcohol alkoxylate used in the composition according to the presentinvention are advantageously presented as aqueous solution. As discussedabove, the cloud point of the composition according to the presentinvention is kept relatively low, which is actually close to roomtemperature. Therefore, when at room temperature or a higher temperaturethat is usually applied in either wool scouring process or lanolinrecovery process, it is easy for the composition of the presentinvention to turn hazy or be further separated into two phases ofalcohol alkoxylate and water, depending on the characteristic ofdifferent alcohol alkoxylates used in the composition. To stabilize theformulation at a high temperature such as the wool scouring temperatureof 65-70° C., a hydrotrope is required to be further added into thecomposition, to solubilize the nonionic surfactant and to enhance thewetting ability of the composition, such that the otherwise insolublenonionic surfactant is dissolved in the solution and may exert itswetting ability. A number of hydrotropes for nonionic surfactants havebeen described in various publications. Generally, the hydrotropesuitable for use in the detergent composition of the present inventionshould be efficient in solubilizing non-ionic surfactants according toabove formula (I).

According to the present invention, the hydrotropes are furtherselected, so as to minimize or eliminate the adverse effects ofhydrotropes on the formulation, such as additional foaming, decreasedlanolin recovery, etc. Example of such a hydrotrope includes, but is notlimited to, bis(ethoxylated) monoalkyl quaternary ammonium compoundhaving the formula (II),

wherein R is C₆-C₂₂ hydrocarbyl, preferably C₆-C₂₂ alkyl or alkenyl,more preferably C₈-C₂₀ alkyl or alkenyl, and most preferably C₁₀-C₁₈alkyl or alkenyl; R¹ is C₁-C₄ alkyl, preferably methyl or ethyl, andmost preferably methyl; x is a number from 1 to 40, y is a number from 1to 40 with the provision that x+y is at least 8, preferably at least 9,and most preferably at least 10, and at most 25, preferably at most 20,and most preferably at most 17; A⁻ is an anion, e.g. halide ormethylsulfate. The value for individual x and y is not critical,however, the combined total is critical as this effects the HLB of thesecompounds. Preferably the ammonium compounds useful in the presentinvention have an HLB of 25.0-31.0 and are very efficient hydrotropesfor nonionic surfactants, therefore they aid in the cleaning performanceof compositions where they are present in combination with nonionicsurfactants.

When used in the composition of the present invention, the weight ratiobetween the alcohol alkoxylate and the bis(ethoyxlated) monoalkylquaternary ammonium compound is from 99:1 to 60:40, and preferably from90:10 to 70:30.

The composition according to the present invention is designed to bediluted in an aqueous system. As the wool varies vastly in grease leveland contamination compositions, the concentration of the detergent inthe final use solution can be adjusted accordingly. Specifically, thetotal amount of the alcohol alkoxylate of formula (I) and, if present,the hydrotrope of formula (II) in said aqueous system is greater than 10ppm, and less than 1000 ppm, preferably greater than 100 ppm, and lessthan 1000 ppm.

In one aspect of the present invention, a method for scouring wool isprovided. The method comprises contacting the wool with a compositioncomprising alcohol alkoxylates with the general formula (I).

According to one of the embodiments of the present invention, thealcohol alkoxylates used in the composition of the present inventionhave a narrow range distribution of alkeleneoxy units, wherein not lessthan 40 wt %, preferably not less than 60 wt %, more preferably not lessthan 70 wt %, of the alcohol alkoxylates has a distribution of theaddition of alkyleneoxy units not greater than 20, preferably notgreater than 9, and more preferably not greater than 7, meanwhile theaddition of alkyleneoxy units is preferably not less than 2, and morepreferably not less than 4.

According to one of the embodiments of the present invention, thealcohol alkoxylates having the general formula (I) are selected fromalcohol ethoxylates, alcohol propoxylates, or a combination thereof,wherein AO represents ethyleneoxy unit, propyleneoxy unit, or acombination thereof, R and n being the same as defined above. In thecase of the combination of alcohol ethoxylates and alcohol propoxylates,the addition of ethylene oxide units is on average within the range of2-9, the addition of propylene oxide unit is on average within the rangeof 0-5.

According to one of the embodiments of the present invention, ahydrotrope selected from bis(ethoxylated) monoalkyl quaternary ammoniumcompound having the formula (II) is included in such an amount that theweight ratio between the alcohol alkoxylate of formula (I) and thebis(ethoyxlated) monoalkyl quaternary ammonium compound of formula (II)is from 99:1 to 60:40, and preferably from 90:10 to 70:30.

According to one of the embodiments of the present invention, thecomposition according to the present invention is designed to be dilutedin an aqueous system to such a concentration that, the total amount ofthe alcohol alkoxylate of formula (I) and, if present, the hydrotrope offormula (II) in said aqueous system is greater than 10 ppm, and lessthan 1000 ppm, preferably greater than 100 ppm, and less than 1000 ppm.

In addition to the above-mentioned components, the composition may alsocontain other optional additives, such as alkyl glucoside, alkylsulphate, alkyl ether sulphate, etc. Moreover, the composition may alsocontain polymeric dispersing agents, chelates, enzymes, pH-controllingagents, bactericides, perfumes, colorants and rheology modifiers, andother components usually appearing in cleaning concentrates.

In yet another aspect of the present invention, the use of thecomposition according to the present invention is provided. Generally,but not for the purpose to limit the present invention into a specificscope, the composition according to the present invention may be used asa detergent in wool scouring processes and/or lanolin recovery.

The advantages achieved by the composition of the present invention areas follows:

1) By using alcohol alkoxylates with low number of alkylene oxide unitsper molecule, the composition of the present invention exhibitsexcellent cleaning efficiency, as compared to conventional detergentsused for wool scouring.

2) The composition of the present invention may result in better lanolinrecovery. As mentioned above, the alcohol alkoxylates with low number ofalkylene oxide units per molecule, while form stable emulsions withlanolin under scouring process, fail to emulsify lanolin in the recoveryprocess where temperature higher than the cloud point is usuallyapplied. Consequently the emulsion break and alcohol alkoxylates mayrelease much more lanolin compared to their higher numbers of alkyleneoxide units counterparts.

3) The composition of the present invention exhibits excellent productstability. It may be stored for a long period without clouding or beingphase-separated, even during the winter time at those cold areas.

DESCRIPTION OF DRAWINGS

The above and other objectives, features and advantages of the presentinvention will become more apparent to those of ordinary skill in theart by describing in embodiments thereof with reference to theaccompanying drawings.

FIG. 1 provides pictures showing whiteness of the wool after rinsing anddrying with different detergent formulations;

FIG. 2 provides pictures showing the results of lanolin recoveryefficiency test on different detergent formulations and at differenttime points;

FIG. 3 provides pictures showing the results of separation test ondifferent detergent formulations.

EXPERIMENTAL

The following examples are offered to illustrate, but not to limit theclaimed invention. Unless otherwise specified, all percentages are byweight.

EXAMPLE 1

Detergent formulations with compositions specified in Table 1 were made.The quanternary ammonium compound was added as a hydrotrope to stabilizethe formulation at elevated temperature and to assist cleaning.

To evaluate the cleaning efficiency of the formulations in Table 1 thefollowing wool scouring test was used. Three 800 gram hot (65-70 C)baths were prepared with only the 2^(nd) one containing the detergentblend (0.01%) while the rest two having just tap water. The dirty rawwool (20 gram) was subsequently washed (5 minutes in each bath),squeezed dry, and transferred to one bath after another. The process wasdesigned to mimic the simplified wool scouring process with the 1^(st)bath for suint deposition, the 2^(nd) one primarily for wool cleaning,and 3^(rd) one for rinsing.

The detergent efficiency was evaluated based on the whiteness of thewool after rinsing and drying, and was summarized in FIG. 1.

TABLE 1 Ingredient #1 #2 #3 #4 #5 C9-11-alcohol + 5.5 EO* 95% 90% 80%70% (Coco alkyl) amine + 15EO  5% 10% 20% 30% quanternized by CH3ClNonyl phenol + 9EO 100% Cleaning efficiency 2** 3 4 5 5 *Narrow rangeethoxylate **scale of whiteness: 5 being the most white, 1 being leastwhite. Numbers are assigned by visual judgment.

Comparing the detergency results with #1, #2, #3, #4, it is evident thatthe increasing concentration of hydrotrope improves the whiteness ofwashed wool. When the blend is composed of 30% of hydrotrope, thewhiteness of the washed wool is comparable to that of the wool washed byNP-9. As the detergency efficiency of the nonionic surfactant isconstrained by its cloud point which is correlated with theconcentration of hydrotrope, this set of scouring results demonstratethat hydrotrope concentration is critical to achieve the optimaldetergency efficiency.

EXAMPLE 2

Hydrotrope Test

In this example formulations were made with a number of hydrotropesspecified in Table 2 to compare hydrotrope efficiency. The less amountof hydrotrope needed to add to turn the formulation to clarity at roomtemperature, the more effective it is as a solubilizing agent. Thenumbers in the Table 2 are expressed in wt. %, and water is added tobalance the total to 100%.

TABLE 2 Ingredient #1 #2 #3 #4 #5 #6 #7 #8 #9 C9-11-alcohol + 4EO* 9.839.75 4.94 4.91 9.75 9.43 9.35 4.81 9.47 wt % wt % wt % wt % wt % wt % wt% wt % wt % (Coco alkyl) amine + 1.67 2.53 1.28 1.86 15EO quanternizedby CH₃Cl Octadecanamine + 2.53 15EO quanternized by CH₃Cl C₈ Alkylglucoside 5.66 6.54 C₆ Alkyl glucoside 3.85 5.30 water Bal.** Bal. Bal.Bal. Bal. Bal. Bal. Bal. Bal. Appearance (RT) s*** c**** s c s s c s c*Narrow range ethoxylate **Bal. = add to balance ***s = separate ****c =clear

EXAMPLE 3

Lanolin Recovery Efficiency Test

In order to compare lanolin recovery efficiency, a series offormulations with 1.00 g detergent, 8.00 g H₂O and 0.50 g lanolin weremixed well, and pictures were taken to characterize the demulsifyingprocess at 70° C.

As shown in FIGS. 2 and 3, arranged from left to right are detergentsC9-11-alcohol+4EO (narrow range ethoxylate), C9-11-alcohol+5.5EO (narrowrange ethoxylate), C9-11-alcohol+6EO (normal range ethoxylate),C9-11-alcohol+8EO (normal range ethoxylate), and Nonylphenol+9EO.

Lanolin was enriched in the nonionic surfactant layer which appears aslight amber color. The results show that C9-11-alcohol+4EO (narrow rangeethoxylate)started demulsifying within 5 minutes, while the rest didn'tstart demulsifying until half hour. C9-11-alcohol+4EO andC9-11-alcohol+5.5EO (both narrow range ethoxylate show more completeseparation than the rest. These results clearly demonstrate that narrowrange alcohol ethoxylates with lower numbers of EO addition haveadvantages over their normal range counterparts in lanolin recovery.Nonylphenol+9EO in comparison shows little if any lanolin enrichmentlayer but has all the lanolin well soluablized in the aqueous layerinstead.

EXAMPLE 4 Low Temperature Stability Test

As the detergent is usually pumped to the washing bath, it is importantto study the stability of the detergent under the cold condition. Aseries of detergent blends with the compositions listed in Table 3 weremixed, and the phase behavior was observed after the blends were storedovernight at 2 degree C. and −22 degree C.

TABLE 3 Ingredient #1 #2 #3 #4 #5 C9-11-alcohol + 5.5 EO* 95% 90% 85%80% 70% (Coco alkyl) amine + 15EO 5% 10% 15% 20% 30% quanternized byCH3Cl *Narrow range ethoxylate

All five blends appeared clear one phase liquid at room temperature.They turned to hazy translucent liquid under 2 degree C. overnight. Nophase separation was observed in any of them. They turned to white solidunder −22 degree C. overnight without phase separation. It is worthnoting that there was no gelling or precipitation happening for theseblends under cold temperature (2 and −22 degree C.), and all sampleswhen taken out of the cold temperature were able to restore to clear onephase liquid without any shaking or mixing when left at roomtemperature. This study demonstrates that these detergent blends exhibitexcellent stability under low temperature. Therefore they are suitablefor use during the winter time at those cold areas.

1. A method for scouring wool, comprising contacting the wool with anaqueous composition comprising an alcohol alkoxylate with the followinggeneral formula (I):RO(AO)_(n)—H   (I) wherein R represents linear or branched hydrocarbylgroup having 4 to 22 carbon atoms, AO represents an alkyleneoxy unithaving 2 to 6 carbon atoms, n is within the range from 1 to 20, and notless than 40 wt % of the alcohol alkoxylates has a distribution of theaddition of alcohol alkyleneoxy units ranging from 2-20.
 2. A methodaccording to claim 1, wherein not less than 40 wt % of the alcoholalkoxylates has a distribution of the addition of alcohol alkyleneoxyunits ranging from 4-9.
 3. A method according to claim 1, wherein notless than 40 wt % of the alcohol alkoxylates has a distribution of theaddition of alcohol alkyleneoxy units ranging from 4-7.
 4. A methodaccording to claim 1, wherein AO is selected from ethylene oxide units,propylene oxide units, or a combination thereof.
 5. A method accordingto claim 3, wherein AO is selected from the combination of ethyleneoxide units and propylene oxide units, with the addition of ethyleneoxide units being within the range of 2-9, and the addition of propyleneoxide units being within the range of 0-5.
 6. A method according toclaim 1, wherein R represents linear or branched hydrocarbyl grouphaving 4 to 22 carbon atoms.
 7. A method according to claim 1, wherein Rrepresents linear or branched hydrocarbyl group having 6 to 13 carbonatoms.
 8. A method according to claim 1, wherein R represents linear orbranched hydrocarbyl group having 9 to 11 carbon atoms.
 9. A methodaccording to claim 1, wherein the composition further comprises ahydrotrope selected from bis(ethoxylated) monoalkyl quaternary ammoniumcompound having the formula (II),

wherein R is C₆-C₂₂ hydrocarbyl, preferably C₆-C₂₂ alkyl or alkenyl,more preferably C₈-C₂₀ alkyl or alkenyl, and most preferably C₁₀-C₁₈alkyl or alkenyl; R¹ is C₁-C₄ alkyl, preferably methyl or ethyl, andmost preferably methyl; x is an number from 1 to 40, y is a number from1 to 40 with the sum of x+y ranging from 8 to 25; and A⁻ is an anion.10. A method according to claim 9, wherein the weight ratio between thealcohol alkoxylate of formula (I) and the hydrotrope of formula (II) isfrom 99:1 to 60:40.
 11. A method according to claim 9 wherein the totalamount of the alcohol alkoxylate of formula (I) and, if present, thehydrotrope of formula (II) in said composition is from 10 to 1000 ppm.